Over the last few months I have noticed that the counter of the number of questions I asked went from 125 to 122. Any idea why? Are questions being purged?
Do (did) you have any closed questions with 0 or negative score and no answers? There is an automatic cleanup of such questions.
There's also the "roomba" which deletes low-scoring, unanswered, low view questions after a year.
Also, if you have anything migrated to another site, the "stub" would be eventually deleted on the original site.